用大地电磁测深法来监测地壳电性随时间变化的初步研究

PRELIMINARY STUDY ON MONITORING THE TEMPORARY CHANGE IN ELECTRICAL PROPERTY IN EARTH CRUST ON EBO SITE, QIJIAN, QINGHAI PROVINCE BY MT METHOD

摘要:

本文讨论了青海祁连俄博测点1979-1985年间的大地电磁测深重复观测结果。观测中选用了磁暴和强磁扰期间的大地电磁记录,保持了观测仪器的较高的稳定性。测点所在地区电磁干扰背景小、地震活动性较强。文中分析了观测记录和资料处理的误差,结果表明,在某些频段内,视电阻率曲线的系统变化和测区周围地区一些5级左右地震活动有着一定的对应关系。

Abstract:

This paper deals with the results of repeated observations in apparent resistivity on Ebo site, Qilian, Qinghai Province from 1979 to 1985 by of MT method. It is suggested that the observationary site is characterized by low noise background and high seismicity around it. During the observation the stability of the instrument was kept very high and the records obtained were taken in the period of magnetic storm or strong magnific disturbance. The error of results were analysed and discussed. It could be found that there were systematic changes in the apparent resistivity in some frequency range associated with the occurrences of earthquakes of M≈5 around the site. It is possible to get the stable impedance tenser apparent resistivity curves and other geophysical function of responses by MT observation with high accuracy, so that MT could be one of the means, which is used to monitor the temperary change of resistivity in the depth corresponding to the focus. Further observation and test of the temperory change of apperent risistivity by MT associated wity earthquake preparatory process is needed.